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Old 15th January 2013, 12:36 PM   #21
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Quote:
Originally Posted by KlipschKid View Post
Quick update - all the changes work as expected except the unity gain. In fact it needs a little gain or it floats.
That's great. Makes me want to take mine apart and modify them. Thanks for sharing.
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Old 15th January 2013, 11:33 PM   #22
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Hi,

I'm happy I found time to try this out. I don't understand why there isn't more info about this reg here. It's simple and it works so well. The 4V dropout for the mosfet isn't so great, but then it has low output impedance so that's a fair trade off.

I let it burn in overnight and had a listen today - no significant difference as far as I can tell - can't do A-B testing to be sure though. However, it's driving 4 op amps with high psrr ( LME49990 ) so that's not too surprising I guess.

Some tech details : my psu is giving +/-15.55 V output unloaded and it drops to 15.50V with a 200mA load. The ccd into the error amp is E-152 so that's 1.5mA +/-10% so I chose the feedback resistors / potential divider as 1K/10K so the current running through that roughly matches @~1.4mA (15.5/11). This also gives just under 10% gain for the two LM329, which are the Vref. For the RC filter after the Vref, I used a 1K res and a 100uF cap. There's a soft start but it's still quick enough. For the caps across Vref, I replaced the electro and used 10uF tantalum and 0.1uF X7R. I haven't tried changing any of the other electrolytics yet - Panasonic FC - but I may if the signature changes.

Anyway, technically, it's lower noise but in my use, that actually hasn't made a heap of difference. It might in more sensitive applications like an I/V for a DAC.

Cheers

Last edited by KlipschKid; 15th January 2013 at 11:38 PM.
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Old 16th January 2013, 02:46 AM   #23
CZ101 is offline CZ101  United States
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Quote:
Originally Posted by Salas View Post
Its not an authorized PCB and it looks like based on an old version. Please don't support the copycats.
Ok thanks for setting the record straight!
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Old 10th July 2013, 11:09 AM   #24
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Just did a noise test on the Kubota from Jims. Seems very quiet at -84dBu (50mA load) My equipment isnt highly calibrated but give or take its a good result. It needs at least 10 v drop to work correctly, 15v dropped the reading by a few extra db.

My test one did have an odd low frequency noise drift. it didnt effect the above result but was visible on the spec analyser. Didnt have much time to investigate and it certianly would not be audible.

Last edited by triplej; 10th July 2013 at 11:18 AM.
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Old 15th July 2013, 08:54 AM   #25
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further testing at a lower current of 20ma I got a figure of -96dBu. You can just see the PSU harmonics (<300hz) rising above the noise floor (after averaging for a while). Thats a level of about -120dB for the harmonics.
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